Evaluation of activation of protein kinase C during agonist-induced constriction of veins isolated from the laminar dermis of horses

Objective—To determine the effects of the protein kinase C (PKC) inhibitor, Ro-31-8220, on agonist-induced constriction of laminar arteries and veins obtained from horses. Sample Population—Laminar arteries and veins obtained from 8 adult mixed-breed horses. Procedures—Laminar arteries and veins were isolated and mounted on small vessel myographs for the measurement of isometric tension. Concentration-response curves were then obtained for the vasoconstrictor agonists phenylephrine, 5-hydroxytryptamine, prostaglandin F2α, and endothelin-1. All responses were measured with or without the addition of Ro-31-8220 (3μM). Results—Laminar veins were more sensitive to vasoconstrictor agonists than laminar arteries, and incubation of laminar veins with Ro-31-8220 resulted in significantly smaller agonist-induced contractile responses for all agonists tested. In contrast, Ro-31-8220 had no effect on agonist-induced contractile responses of laminar arteries. Conclusions and Clinical Relevance—Results of the study we...